THE CAROTENE-cancer findings may be news to the public -- and to health food store owners, who are rubbing their hands in glee -- but researchers have been ready for the results for a long time.
A study just published in the English medical journal Lancet suggests that carotene could play some role in protecting against lung cancer. Like most nutrition news, this is a good news/bad news story. And its moral is familiar.
Beta-carotene (also called pro-vitamin A) is a substance found in plants -- specifically dark green leafy vegetables, broccoli, carrots, deep orange winter squashes and yams, apricots, cantaloupe and peaches. It is converted by animals (including man) into vitamin A. Vitamin A plays a role in cell differentiation, "the basic process of cell development," or maturation. As a result, the vitamin has been examined for about 15 years to see if it might prevent cancer -- which is a perversion of cell growth.
The study of this vitamin's relationship to cancer is not new. Dr. Michael Sporn, chief of the Laboratory of Chemoprevention at the National Institutes of Health, who has studied it for the last 10 years, says, "This is one further confirmatory study. This has been written about multiple times, not only in newspapers but in journals."
In a March 1981 article for Nature, Sporn and his associates reported that 324 research papers dealing with cancer and vitamin A had been collected at the National Cancer Institute in Bethesda. The collection reports all kinds of cancer inhibition studies using many different experimental techniques. Sporn's article raised a specific question: Is it the active form of vitamin A, or its precursor beta-carotene, which may suppress cancer?
"Our paper is a scientific paper responding to that question," said Dr. Richard Shekelle, one of the researchers involved in the Lancet report. "We are not claiming there's a cure for cancer or to go on a carrot diet . . ."
Dr. D. James Morre', director of Purdue University's cancer center, said he doesn't "think much will happen in the scientific world" as a result of the Lancet article. "This is not an unexpected finding. The place where things will happen is in the health food stores.
"My reaction to it the study ," he said, "would be that the possibility that vitamin A or pro-vitamin A has some sort of preventive action is a very exciting possibility. We didn't need this study to fan our enthusiasm. What's really necessary is a good, controlled study to prove that it's really what we think it is. I feel uncomfortable with any of these things until we know the mechanism."
The good news, then, is the possibility that accessible, inexpensive, apparently harmless substances may help prevent the country's most dread disease. The bad news is that the mechanism of cancer suppression is unknown. Until it is known, researchers refuse to draw absolute conclusions as to cause and effect.
Shekelle's study is an observational study -- the researchers looked at about 2,000 Western Electric workers over 19 years to see what happened. Those who had a diet higher in beta-carotene at the beginning of the study seemed to have a lower incidence of lung cancer at the end. The mechanism -- the thing that actually happened in their bodies to prevent the cancer from growing -- is unknown.
Shekelle says "there is no dearth" of subjects for follow-up studies -- many questions remain. Still unknown is how much beta-carotene triggers a specific reaction. Also, does isolated beta-carotene have the same effect as that consumed in the diet?
The scientists will sit tight, wait and see as experiments continue.
Dr. Stanley Gershoff, dean of Tufts School of Nutrition, offers his opinion of how the consumer will translate the news. "A lot of people will start selling beta-carotene and making a lot of money," he said, predicting that the average person will perceive beta-carotene consumption as an easy answer to the pervasive threat of cancer. "People want to believe those things.
"You know what a lot of people will say . . . 'Thank God I can go back to smoking,' " he said, laughing. "Tell people this is a preliminary study; there's no basis for running out and eating a lot of beta-carotene, that people who are smoking are still at great risk of lung cancer."
For people interested in increasing the natural sources of beta-carotene in their diet, the following recipes may prove useful.
INDIAN CABBAGE (6 to 8 servings) 1 head bok choy, shredded 3 tablespoons butter 1 tablespoon cumin 1/2 cup buttermilk 1 tablespoon lemon juice 1 tablespoon crushed mint Salt and ground red chiles to taste
Soak bok choy in cold salted water for 20 minutes. Drain and dry thoroughly. Heat butter in large saucepan and stir in cumin and bok choy. Cook, stirring occasionally, over low heat for 10 minutes. Add buttermilk, lemon juice, mint, salt and red pepper to taste. Cook, stirring, over low heat until slightly glazed.
PAULA WOLFERT'S MOROCCAN CARROT SALAD (8 servings) 2 pounds carrots 1 clove garlic 1/2 teaspoon ground cinnamon 1 teaspoon ground cumin 1 teaspoon paprika 2 pinches cayenne (optional) Juice of 2 lemons 1/2 teaspoon sugar Salt to taste Olive oil Chopped parsley
Wash and peel the carrots. Boil whole in water with the garlic until barely tender. Drain. Discard the garlic and dice or slice the carrots; the pieces should be large, as in Morocco this would be eaten with the hands.
Combine cinnamon, cumin, paprika, cayenne, lemon juice, sugar and salt and pour over carrots. Chill. Sprinkle with oil and chopped parsley just before serving.
CARROT AND BUTTERNUT SQUASH CASSEROLE (8 servings) 1 1/2 pounds butternut squash, peeled, seeded and diced 3 cups peeled, sliced carrots Chicken stock (optional) 3/4 cup light cream 6 tablespoons butter Salt, white pepper and cayenne pepper to taste Minced parsley for garnish
In a large saucepan, cook vegetables to cover with half water and half chicken stock or all water until tender. Drain vegetables and transfer to a bowl of a food processor fitted with a steel blade. Add cream, butter and seasonings and process for a few seconds until ingredients are combined but not pure'ed. Scrape into buttered casserole dish and bake in a preheated 350-degree oven for 15 minutes. Sprinkle with minced parsley and serve.
EASY PUMPKIN BREAD (Makes 1 loaf) 2 cups flour 1 1/2 teaspoons baking powder 1/4 teaspoon baking soda 1 1/2 teaspoons cinnamon 1/2 teaspoon allspice 1/4 teaspoon ginger 1 3/4 cups sugar 2/3 cup salad oil 2 eggs 1 1/3 cups pumpkin 1/2 cup raisins 1/2 cup chopped nuts (optional)
Sift flour, baking powder and soda, cinnamon, allspice and ginger. Set aside. Combine sugar with oil in large bowl. Beat in eggs one at a time. Stir in pumpkin, then flour. Stir until well combined. Pour into greased and floured 9-by-5-inch loaf pan and bake at 350 degrees for 30 minutes. Reduce heat to 325 and bake 45 minutes more. It makes a very moist loaf.